1. Field of the Invention
The present invention relates to a hard disk drive device used as a small-size storage device for a computer, for example.
2. Description of the Related Art
Conventionally, information is written and read to/from a hard disk (HDD) by a magnetic head and a magnetic disk.
In the HDD, a magnetic head, a magnetic disk, a head positioning mechanism, a spindle motor, and the like are formed with precision mechanism elements. Therefore, it is necessary to prevent intrusions of dust and the like.
Among the conventional HDDs, there is such a type in which a breathing hole having a filter and a gas absorber is provided in a casing in order to overcome a difference between the inside pressure and the outside pressure generated due to an increase in the inside pressure at the time of operation. There is also known a hard disk drive device in a structure that has a screw hole opened through a disk enclosure (HDA).
Further, while HDD-loaded products are conventionally placed under environments where the temperature/humidity are kept to specific values, e.g., in business premises, computer rooms, data centers, etc., such products have come to be placed in various environments (environments where the temperature/humidity exceed the temperature/humidity environment specification for HDD alone) recently in accordance with expansions in the fields using such products. Therefore, there is an increasing risk of deteriorating the long-term reliability of HDD because of a had influence imposed upon the magnetic head, the magnetic disk, etc., due to intrusion of humidity into the inside of the HDD.
Thus, there has been taken a measure by makers of each HDD, such as increasing the constant under humid environments, for example, by employing a labyrinth structure to a breathing hole part which suppresses intrusion of humidity into the inside of the HDD, for example.
As an HDD that is formed not to be affected by the temperature, humidity, and a difference between the inside pressure and outside pressure in case of HDD-loaded product, there is known a closed hard disk which is proposed to prevent dew condensation, generated in a pressure bearing part caused by changes in the humidity, temperature, and the like, to make it possible to stably start up and rotate a spindle motor (see Japanese Unexamined Patent Publication 2000-331458 (Patent Document 1), for example).
The closed hard disk disclosed in Patent Document 1 is formed as a structure in which bellows are provided on one side of a housing so as to absorb the changes in the outside pressure by the bellows.
Further, there is also known a compressor that is capable of securing a sealing property by preventing fixation of an O-ring of a shaft sealing unit for a revolving shaft (see Japanese Unexamined Patent Publication 2007-077958 (Patent Document 2), for example).
In the compressor of Patent Document 2, disclosed is a structure in which a seal member is pressed by a spring structure.
Further, there is known a filter bank device which is proposed so that unfiltered air that passes through a filter bank is not completely leaked (see Japanese Unexamined Patent Publication Sho 62-042720 (Patent Document 3), for example).
In the filter bank device of Patent Document 3, disclosed is a structure capable of being sealed by inserting a gel-type material as a seal member and pressing a filter as illustrated in the drawing.
Furthermore, there is known a hard disk drive device in a structure that is capable of keeping complete airtightness, avoiding deformation of the external structure of a casing, and achieving a secured high reliability (see Japanese Unexamined Patent Publication Hei 05-074129 (Patent Document 4), for example).
In the hard disk drive device of Patent Document 4, disclosed as a second exemplary embodiment is a case where a breathing hole is opened on a top cover. In this case, the breathing hole is covered by a thin-plate in a bellows structure of a required size.
However, with the typical HDD, humidity intrudes inside the HDD from the breathing hole and the screw hole. Therefore, there is a change generated in the initial manufacture humidity set in advance, and the change in the humidity gives a bad influence on the magnetic head, the magnetic disk, and the like. As a result, the long-term reliability of the HDD is deteriorated.
Further, in the closed hard disk disclosed in Patent Document 1, the bellows are provided inside the housing. Thus, the proportion of the bellows becomes large, which is an obstacle to reduce the size of the device. Additionally, since the bellows are provided inside the housing, it is necessary to first remove the cover part from the housing before attaching and detaching the bellows, which is uneasy to do. Also, it is difficult to be used repeatedly.
Further, in the compressor disclosed in Patent Document 2, the seal member is not a gel-type member, and the part to be sealed is also different.
Furthermore, in the filter bank device disclosed in Patent Document 3, a gel-type material is inserted as a seal member. However, the outer circumference of the gel-type material is covered by a seal member holding frame, so that it is not freely detachable.
Furthermore, in the hard disk drive device disclosed in Patent Document 4, the breathing hole is covered by a bellows-structured thin plate formed in a required size. However, the bellows-structured thin plate is provided inside the breathing hole, so that a space for providing the thin plate is necessary. This is an obstacle to reduce the size of the hard disk drive device. The present invention is proposed to overcome each of the above-described issues. It is an exemplary object of the present invention to provide a hard disk drive device formed in a small size, which can keep the humidity inside the drive to the initial manufacture humidity over a long term and adjust the difference between the pressures of the inside and outside the device.